Though a border wall with Mexico is currently a matter of serious discussion in the United States, the aim of which is to prevent the physical movement of people (with few other apparent “benefits”), some walls can actually bring together and preserve communities, rather than divide them.In only five years, the UN says, around 60 million Africans may be displaced as their land ceases to be arable, a potential humanitarian disaster the scale of which would be unprecedented. This would be devastating to a huge portion of the African continent not only ecologically and economically but socially as well.That’s where Africa’s ingenious Great Green Wall comes in.Experts at the United Nations say without action, desertification may claim two-thirds of Africa’s farmlands in under a decade. The Great Green Wall, however, was conceived as a wide-reaching strategy to halt Northern Africa’s rapidly advancing Sahara Desert.The Great Green Wall, once complete, will stretch an incredible 4,400 miles from Senegal in West Africa to the East African nation of Djibouti. Instead of bricks and mortar, the wall will be made of trees and other vegetation, including plants that can be eaten or used to create medicine.